Digital broadcasting system and method of processing data

ABSTRACT

A digital broadcasting system and a method of processing data are disclosed. The method of processing data of a transmitting system includes generating signaling information including service-related transmission parameters of mobile service data, packetizing the generated signaling information to a predetermined data packet format, primarily multiplexing the packetized signaling information and a mobile service data packet including the mobile service data, and secondarily multiplexing the primarily multiplexed data packets and a main service data packet including main service data, thereby transmitting the secondarily multiplexed data packets to at least one transmitter located in a remote site.

This application is a continuation reissue application of U.S. Reissueapplication Ser. No. 14/519,290, filed on Oct. 21, 2014, currentlypending, which is a reissue application of U.S. Pat. No. 8,396,088 B2,issued from U.S. patent application Ser. No. 12/890,459, filed on Sep.24, 2010, which is a continuation of U.S. application Ser. No.12/019,194, filed on Jan. 24, 2008, now U.S. Pat. No. 7,826,498, whichclaims the benefit of earlier filing date and right of priority toKorean Patent Application No. 10-2007-0036700, filed on Apr. 14, 2007,and also claims the benefit of U.S. Provisional Application Ser. No.60/886,469, filed on Jan. 24, 2007, the contents of all of which are allhereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital broadcasting system and amethod of processing data.

2. Discussion of the Related Art

The Vestigial Sideband (VSB) transmission mode, which is adopted as thestandard for digital broadcasting in North America and the Republic ofKorea, is a system using a single carrier method. Therefore, thereceiving performance of the receiving system may be deteriorated in apoor channel environment. Particularly, since resistance to changes inchannels and noise is more highly required when using portable and/ormobile broadcast receivers, the receiving performance may be even moredeteriorated when transmitting mobile service data by the VSBtransmission mode.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a digital broadcastingsystem and a method of processing data that substantially obviate one ormore problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a digital broadcastingsystem and a method of processing data that are highly resistant tochannel changes and noise.

Another object of the present invention is to provide a digitalbroadcasting system and a method of processing data that can enhance thereceiving performance by performing additional encoding on mobileservice data and by transmitting the processed data to the receivingsystem.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod of processing data in a transmitting system includes generatingsignaling information including service-related transmission parametersof mobile service data, packetizing the generated signaling informationto a predetermined data packet format, primarily multiplexing thepacketized signaling information and a mobile service data packetincluding the mobile service data, and secondarily multiplexing theprimarily multiplexed data packets and a main service data packetincluding main service data, thereby transmitting the secondarilymultiplexed data packets to at least one transmitter located in a remotesite. Herein, the predetermined data packet format may correspond to anoperations and maintenance (OM) packet.

The method may further include generating null data packets. In thiscase, in the step of primarily multiplexing data packets, a plurality ofnull data packets, the mobile service data packet including the mainservice data, and the OM packet including the signaling information maybe multiplexed at a predetermined data rate, and then transmitted. Also,the transmission parameters may each include at least one of informationuniquely identifying a specific mobile service, super frame information,burst information, turbo code information, and RS code information.

In another aspect of the present invention, a method of processing datain a transmitting system includes generating signaling informationincluding service-related transmission parameters of mobile servicedata, inserting the generated signaling information in a payload regionof an operations and maintenance (OM) packet, primarily multiplexing theOM packet and a mobile service data packet including the mobile servicedata, and secondarily multiplexing the primarily multiplexed datapackets and a main service data packet including main service data,thereby transmitting the secondarily multiplexed data packets to atleast one transmitter located in a remote site.

In a further aspect of the present invention, a transmitting systemincludes a first packet generator, a mobile service multiplexer, and atransport multiplexer. The first packet generator generates signalinginformation including service-related transmission parameters of mobileservice data, and packetizes the generated signaling information to apredetermined data packet format. The mobile service multiplexerprimarily multiplexes the packetized signaling information and a mobileservice data packet including the mobile service data. And, thetransport multiplexer secondarily multiplexes the primarily multiplexeddata packets and a main service data packet including main service data,thereby transmitting the secondarily multiplexed data packets to atleast one transmitter located in a remote site.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a block diagram showing a general structure of atransmitting system according to an embodiment of the present invention;

FIG. 2 illustrates a block diagram showing an example of a servicemultiplexer of FIG. 1;

FIG. 3 illustrates an example of an OM packet syntax structure accordingto the present invention;

FIG. 4A and FIG. 4B respectively illustrate examples of SI packet syntaxstructures according to the present invention;

FIG. 5 illustrates another example of an ON packet syntax structureaccording to the present invention;

FIG. 6 illustrates an example of a turbo code mode within a transportparameter according to the present invention;

FIG. 7A and FIG. 7B respectively illustrate examples of RS code modewithin a transport parameter according to the present invention;

FIG. 8A and FIG. 8B respectively illustrate examples of allocating PIDsof PSI/PSIP tables for main service and mobile service;

FIG. 9 illustrates a block diagram showing an example of a transmitterof FIG. 1;

FIG. 10 illustrates a block diagram showing an example of apre-processor of FIG. 9;

FIG. 11A and FIG. 11B illustrate data configuration before and after adata deinterleaver in a transmitting system according to the presentinvention; and

FIG. 12 illustrates a block diagram showing a structure of a receivingsystem according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

Among the terms used in the description of the present invention, mainservice data correspond to data that can be received by a fixedreceiving system and may include audio/video (A/V) data. Morespecifically, the main service data may include A/V data of highdefinition (HD) or standard definition (SD) levels and may also includediverse data types required for data broadcasting. Also, the known datacorrespond to data pre-known in accordance with a pre-arranged agreementbetween the receiving system and the transmitting system. Additionally,in the present invention, mobile service data may include at least oneof mobile service data, pedestrian service data, and handheld servicedata, and are collectively referred to as mobile service data forsimplicity. Herein, the mobile service data not only correspond tomobile/pedestrian/handheld service data (M/P/H service data) but mayalso include any type of service data with mobile or portablecharacteristics. Therefore, the mobile service data according to thepresent invention are not limited only to the M/P/H service data.

The above-described mobile service data may correspond to data havinginformation, such as program execution files, stock information, and soon, and may also correspond to A/V data. Most particularly, the mobileservice data may correspond to A/V data having lower resolution andlower data rate as compared to the main service data. For example, if anA/V codec that is used for a conventional main service corresponds to aMPEG-2 codec, a MPEG-4 advanced video coding (AVC) or scalable videocoding (SVC) having better image compression efficiency may be used asthe A/V codec for the mobile service. Furthermore, any type of data maybe transmitted as the mobile service data. For example, transportprotocol expert group (TPEG) data for broadcasting real-timetransportation information may be serviced as the main service data.

Also, a data service using the mobile service data may include weatherforecast services, traffic information services, stock informationservices, viewer participation quiz programs, real-time polls andsurveys, interactive education broadcast programs, gaming services,services providing information on synopsis, character, background music,and filming sites of soap operas or series, services providinginformation on past match scores and player profiles and achievements,and services providing information on product information and programsclassified by service, medium, time, and theme enabling purchase ordersto be processed. Herein, the present invention is not limited only tothe services mentioned above. In the present invention, the transmittingsystem provides backward compatibility in the main service data so as tobe received by the conventional receiving system. Herein, the mainservice data and the mobile service data are multiplexed to the samephysical channel and then transmitted.

Particularly, the present invention uses a transport multiplexer used ina conventional digital broadcasting system so as to multiplex the mobileservice data. Additionally, the transmitting system according to thepresent invention encapsulates non-transport-packet-stream mobileservice data (i.e., mobile service data that are not in TS packetformats) into TS packet formats, thereby outputting the encapsulateddata. Furthermore, the transmitting system according to the presentinvention performs additional encoding on the mobile service data andinserts the data already known by the receiving system and transmittingsystem (e.g., known data), thereby transmitting the processed data.Therefore, when using the transmitting system according to the presentinvention, the receiving system may receive the mobile service dataduring a mobile state and may also receive the mobile service data withstability despite various distortion and noise occurring within thechannel.

FIG. 1 illustrates a block diagram showing a general structure of atransmitting system according to an embodiment of the present invention.Herein, the transmitting includes a service multiplexer 100 and atransmitter 200. Herein, the service multiplexer 100 is located in thestudio of each broadcast station, and the transmitter 200 is located ina site placed at a predetermined distance from the studio. Thetransmitter 200 may be located in a plurality of different locations.Also, for example, the plurality of transmitters may share the samefrequency. And, in this case, the plurality of transmitters receives thesame signal. This corresponds to a data transmission using a singlefrequency network (SFN). Accordingly, in the receiving system, a channelequalizer may compensate signal distortion, which is caused by areflected wave, so as to recover the original signal. In anotherexample, the plurality of transmitters may have different frequencieswith respect to the same channel. This corresponds to a datatransmission using a multiple frequency network (MFN).

A variety of methods may be used for data communication each of thetransmitters, which are located in remote positions, and the servicemultiplexer. For example, an interface standard such as a synchronousserial interface for transport of MPEG-2 data (SMPTE-310M). In theSMPTE-310M interface standard, a constant data rate is decided as anoutput data rate of the service multiplexer. For example, in case of theSVSB mode, the output data rate is 19.39 Mbps, and, in case of the 16VSBmode, the output data rate is 38.78 Mbps. Furthermore, in theconventional 8VSB mode transmitting system, a transport stream (TS)packet having a data rate of approximately 19.39 Mbps may be transmittedthrough a single physical channel. Also, in the transmitting systemaccording to the present invention provided with backward compatibilitywith the conventional transmitting system, additional encoding isperformed on the mobile service data. Thereafter, the additionallyencoded mobile service data are multiplexed with the main service datato a TS packet form, which is then transmitted. At this point, the datarate of the multiplexed TS packet is approximately 19.39 Mbps.

At this point, the service multiplexer 100 receives at least one type ofmain service data and program specific information/program and systeminformation protocol (PSI/PSIP) table data for each main service so asto encapsulate the received data to a TS packet. Also, the servicemultiplexer 100 receives at least one type of mobile service data andPSI/PSIP table data for each mobile service and encapsulates thereceived data to transport stream (TS) packets. Subsequently, the TSpackets are multiplexed according to a predetermined multiplexing ruleand outputs the multiplexed packets to the transmitter 200.

FIG. 2 illustrates a block diagram showing an example of the servicemultiplexer. The service multiplexer includes a main service PSI/PSIPgenerator 110, a mobile service PSI/PSIP generator 120, a systeminformation (SI) packet generator 130, a null packet generator 140, amobile service multiplexer 150, and a transport multiplexer 160. Thetransport multiplexer 160 may include a main service multiplexer 161 anda transport stream (TS) packet multiplexer 162. Referring to FIG. 2, atleast one type of compression encoded main service data and the PSI/PSIPtable data generated from the main service PSI/PSIP generator 110 areinputted to the main service multiplexer 161 of the transportmultiplexer 160. The main service multiplexer 161 encapsulates each ofthe inputted main service data and PSI/PSIP table data to MPEG-2 TSpacket forms. Then, the MPEG-2 TS packets are multiplexed and outputtedto the TS packet multiplexer 162. Herein, the data packet beingoutputted from the main service multiplexer 161 will be referred to as amain service data packet for simplicity.

Thereafter, at least one type of the compression encoded mobile servicedata and the PSI/PSIP table data generated from the mobile servicePSI/PSIP generator 130 are inputted to the mobile service multiplexer150. The mobile service multiplexer 150 encapsulates each of theinputted mobile service data and PSI/PSIP table data to MPEG-2 TS packetforms. Then, the MPEG-2 TS packets are multiplexed and outputted to theTS packet multiplexer 162. Herein, the data packet being outputted fromthe mobile service multiplexer 150 will be referred to as a mobileservice data packet for simplicity.

At this point, the transmitter 200 requires identification informationin order to identify and process the main service data packet and themobile service data packet. Herein, the identification information mayuse values pre-decided in accordance with an agreement between thetransmitting system and the receiving system, or may be configured of aseparate set of data, or may modify predetermined location value with inthe corresponding data packet. As an example of the present invention, adifferent packet identifier (PID) may be assigned (or allocated) toidentify each of the main service data packet and the mobile servicedata packet. More specifically, by allocating a PID that is not used inthe main service to the mobile service, the transmitter 200 may be ableto refer to the PID of the data packet that is being received, therebybeing capable of identifying (or distinguishing) the main service datapacket and the mobile service data packet.

In another example, by modifying a synchronization data byte within aheader of the mobile service data, the service data packet may beidentified by using the synchronization data byte value of thecorresponding service data packet. For example, the synchronization byteof the main service data packet directly outputs the value decided bythe ISO/IEC13818-1 standard (i.e., 0x47) without any modification. Thesynchronization byte of the mobile service data packet modifies andoutputs the value, thereby identifying the main service data packet andthe mobile service data packet. Conversely, the synchronization byte ofthe main service data packet is modified and outputted, whereas thesynchronization byte of the mobile service data packet is directlyoutputted without being modified, thereby enabling the main service datapacket and the mobile service data packet to be identified.

A plurality of methods may be applied in the method of modifying thesynchronization byte. For example, each bit of the synchronization bytemay be inversed, in other words, bitwise inversion may be performed(e.g., 0xB8), or only a portion of the synchronization byte may beinversed (e.g., 0x48). As described above, any value that can be used toidentify the main service data packet and the mobile service data packetmay be used as the identification information. Therefore, the scope ofthe present invention is not limited only to the example set forth inthe description of the present invention.

Meanwhile, a transport multiplexer used in the conventional digitalbroadcasting system may be used as the transport multiplexer 160according to the present invention. More specifically, in order tomultiplex the mobile service data and the main service data and totransmit the multiplexed data, the data rate of the main service islimited to a data rate of (19.39-K) Mbps. Then, K Mbps, whichcorresponds to the remaining data rate, is assigned as the data rate ofthe mobile service. Thus, the transport multiplexer which is alreadybeing used may be used as it is without any modification. Herein, thetransport multiplexer 160 multiplexes the main service data packet beingoutputted from the main service multiplexer 161 and the mobile servicedata packet being outputted from the mobile service multiplexer 150.Thereafter, the transport multiplexer 160 transmits the multiplexed datapackets to the transmitter 200 at a constant data rate (e.g., a datarate of 19.39 Mbps).

However, in some cases, the output data rate of the mobile servicemultiplexer 150 may not be equal to K Mbps. For example, when theservice multiplexer 100 assigns K Mbps of the 19.39 Mbps to the mobileservice data, and when the remaining (19.39-K) Mbps is, therefore,assigned to the main service data, the data rate of the mobile servicedata that are multiplexed by the service multiplexer 100 actuallybecomes lower than K Mbps. This is because the pre-processor of thetransmitter 200 performs additional encoding on the mobile service data,thereby increasing the amount of data. Eventually, the data rate of themobile service data, which may be transmitted from the servicemultiplexer 100, becomes smaller than K Mbps.

For example, since the pre-processor of the transmitter 200 performs anRS frame encoding process and an encoding process on the mobile servicedata at a coding rate of at least ½, the amount of the data outputtedfrom the pre-processor is increased to more than twice the amount of thedata initially inputted to the pre-processor. Therefore, the outputteddata rate of the mobile service multiplexer 150 is always smaller thanK/2. Accordingly, the sum of the data rate of the main service data andthe data rate of the mobile service data, both being multiplexed by theservice multiplexer 100, becomes smaller than 19.39 Mbps.

The service multiplexer 100 of the present invention may match (or putin accord) the data rate of the final output data of the mobile servicemultiplexer 150 to a constant rate (e.g., K Mbps) according to variousembodiments of the present invention. In an embodiment, the Si packetgenerator 130 generates a transmission parameter including a signalinginformation (SI) packet related (or associated) with the mobile service.Thereafter, the mobile service multiplexer 150 may multiplex the SIpacket and the mobile service data packet. In another embodiment, thenull packet generator 140 generates a null data packet. Then, the mobileservice multiplexer 150 may multiplex the null data packet and themobile service data packet. Herein, the mobile service data packetincludes at least one of mobile service data and PSI/PSIP table data. Atthis point, the mobile service multiplexer 150 may multiplex the mobileservice data packet and the SI packet, thereby matching (or fixing) thedata rate of the output data to K Mbps. Alternatively, the mobileservice multiplexer 150 may multiplex the mobile service data packet,the SI packet, and the null data packet, thereby matching (or fixing)the data rate of the output data to K Mbps. Furthermore, the mobileservice multiplexer 150 may also multiplex the mobile service datapacket and the SI packet, thereby matching (or fixing) the data rate ofthe output data to K Mbps.

The SI packet is generated for two reasons. One of the reasons forgenerating the SI packet is to match (or fix) the output data rate ofthe mobile service multiplexer 150 to a constant rate. The other reasonfor generating the SI packet is to provide a transmission parameter tothe transmitter 200, which requires the transmission parameter toprocess the mobile service data. Furthermore, a plurality of mobileservice types may be inputted to the mobile service multiplexer 150.When a plurality of mobile service types is being inputted, and when aplurality of mobile service data types is transmitted from thetransmitter in the form of burst units, only one mobile service datatype may be set to be included in one burst-on section. In this case,each of the plurality of mobile service data types is identified inburst units. Therefore, in order to enable the transmitter 200 toreceive the plurality of mobile service data types and to transmit thereceived data types in burst units, each mobile service is required tobe identified.

For this, according to an embodiment of the present invention, the SIpacket generator 130 generates a SI packet so that the generated SIpacket and the mobile service data packet can be multiplexed on aone-to-one (1:1) basis. At this point, the SI packet generator 130 mayallocate at least one field in the payload portion of the SI packet andmay also indicate information required for identifying the mobileservices (e.g., mobile service identifiers) on the allocated field andoutput the processed data (or packet). More specifically, the SI packetgenerator 130 generates a SI packet of the corresponding mobile servicedata packet, which is to be multiplexed on a one-to-one (1:1) basis bythe mobile service multiplexer 150. Then, the generated SI packet to themobile service multiplexer 150. Accordingly, by parsing the fieldallocated to the payload of the SI packet, the transmitter 200 may becapable of identifying each of the mobile service. This method is moreefficient when the method is applied to an embodiment, wherein asynchronization byte is used as the transmission parameter foridentifying (or distinguishing) the mobile service data packet and themain service data packet. At this point, the transmitter 200 requires anidentification information for identifying the SI packet, so that thetransmitter 200 can identify the SI packet and extract a transmissionparameter from the identified SI packet.

According to an embodiment of the present invention, the SI packet isinserted in a payload region (or field) within an operations andmaintenance (OM) packet (or OMP). Accordingly, the transmitter 200 maybe able to indicate an identification information that can recognize (oracknowledge) whether or not an SI packet has been inserted in an OM_typefield of the corresponding OM packet. More specifically, a packetreferred to as an OMP is defined for the purpose of operating andmanaging the transmitting system. For example, the OMP is configured inaccordance with the MPEG-2 TS packet format, and the corresponding PIDis given the value of 0x1FFA. The OMP is configured of a 4-byte headerand a 184-byte payload. Herein, among the 184 bytes, the first bytecorresponds to an OM_type field, which indicates the type of the OMpacket. Also, the remaining 183 bytes correspond to an OM_payload field,wherein actual data bytes are inserted. In the present invention, amongthe values of the reserved fields within the OM_type field, apre-arranged value is used, thereby indicating that the SI packet hasbeen inserted in the corresponding OM packet. Accordingly, thetransmitter 200 may find (or identify) the OMP by referring to the PID.Also, by parsing the OM_type field within the OMP, the transmitter 200can verify whether the SI packet has been inserted in the correspondingOM packet.

FIG. 3 illustrates a syntax structure of the OM packet according to anembodiment of the present invention. Particularly, FIG. 3 shows a184-byte syntax configuration (or structure) excluding the 4-byte packetheader. Herein, FIG. 3 shows an example of inserting a SI packet(SI_packet( )) within an OM_payload field located after the OM_typefield, transmitting a transmission parameter related (or associated)with the mobile service. Although the size of the OM_payload field ofthe ON packet is equal to 183 bytes, the size of the SI packet may besmaller than or equal to 183 bytes. If the size of the SI packet issmaller than 183 bytes, the remaining bytes may be filled with stuffingbytes by the stuffing_byte field following the service_information( )field. Herein, the stuffing_byte field is repeated as much as thelacking number of bytes, thereby maintaining the OM_payload portion ofthe corresponding OM packet to 183 bytes. More specifically, thestuffing_byte field is assigned with 8 bits, which indicates data bytesused for filling (or completing) the empty data space within thepayload. At this point, the value N1 corresponding to the number oftimes the stuffing_byte field is repeated (i.e., the length of thestuffing byte) represents 183—[the length of the SI_packet( ) field].

The transmission parameters transmitted to the SI packets correspond tosignaling information required by the transmitter and/or the receivingsystem for processing the mobile service data. Examples of thetransmission parameter may include a mobile service identificationinformation, a data group information, a region information within aspecific data group, a RS frame information, a super frame information,a burst information, a turbo code information, a RS code information,and so on. The burst information includes a burst size information, aburst period information, a time to next burst (TNB) information, and soon. Herein, a burst period refers to a cycle period according to which aburst that transmits the same type of mobile service is being repeated.The burst size indicates the number of data groups included in a singleburst. Also, the data group includes a plurality of mobile service datapackets, and a plurality of such data groups is grouped to configure aburst. The burst section indicates the beginning (or starting) point ofthe current burst up to the beginning (or starting) point of the nextburst. Herein, the burst section includes a section including the datagroup (also referred to as a burst-on section) and a section notincluding the data group (also referred to as a burst-off section). Morespecifically, a burst-on section consists of a plurality of fields,wherein one field may include on data group.

Furthermore, the transmission parameter may also include information onan encoding method used for encoding symbol region signals fortransmitting the mobile service data, and also multiplexing informationon how the multiplexing is performed on the main service data and mobileservice data, or on a plurality of mobile service data types. Theinformation included in the transmission parameter are merely exemplaryto facilitate the understanding of the present invention. And, theadding and deleting of the information included in the transmissionparameter may be easily modified and changed by anyone skilled in theart. Therefore, the present invention is not limited to the examplesproposed in the description set forth herein.

FIG. 4A illustrates an exemplary syntax structure of a SI packetgenerated from the SI packet generator 130. Herein, the SI packet may beinserted in an OM_payload field within the OM packet of FIG. 3. At thispoint, the OM packet having the SI packet inserted therein may either begenerated from the SI packet generator 130, or be generated from themobile service multiplexer 150. Furthermore, the mobile service datapacket and the OM packet are multiplexed by the mobile servicemultiplexer 150 and then outputted. Referring to FIG. 4A, the SI packetstructure corresponds to an example of the SI packet being in aone-to-one correspondence with a single mobile service. At this point,the OM packet including the SI packet and the mobile service data packetmay be multiplexed on a one-to-one (1:1) basis and then transmitted.

Referring to FIG. 4A, the SI_packet( ) field includes a service_idfield, a program_number field, a burst_period field, a super_frame_sizefield, a burst_size field, a turbo_code_mode field, and a RS_code_modefield. Herein, the terminology mentioned in the SI_packet( ) field, suchas data group, region of the data group, super frame, burst, turbo codemode, RS code mode, and so on, will be briefly described whiledescribing each of the corresponding fields. Furthermore, theabove-mentioned terms will be described in more detail when describingthe transmitter 200 with reference to FIG. 9 in a later process.

In the embodiment of the present invention, the service_id field is an8-bit field, which indicates a mobile service identifier (i.e., mobileservice ID) that can solely identify each of the mobile services (orprograms). For example, when transmitting multiple mobile service datatypes, the service_id field may be used as an identifier fordistinguishing the plurality of mobile services. The program_numberfield is assigned with 16 bits. Herein, for example, the program_numberfield indicates a number of a program related to a mobile servicedefined by the PSI/PSIP table.

The burst_period field is an 8-bit field, which indicates the cycleperiod of a burst (i.e., burst period). More specifically, when thetransmitter 200 transmits mobile service data in burst units, theburst_period field is used to indicate a repetition period of a burstthat transmits identical types of mobile services. Herein, the number ofdata fields indicates the burst repetition period. The burst_periodfield corresponds to one of the transmission parameters that aretransmitted to the receiving system along with the corresponding mobileservice data from the transmitter 200. Herein, 4 reserved bits may beallocated after the burst_period field.

The super_frame_size field is a 4-bit field, which indicates the size ofa super frame. More specifically, the transmitter 200 configures a RSframe so as to perform error correction encoding. Then, the transmitter200 groups a plurality of error correction encoded RS frames, therebyconfiguring a super frame. The transmitter 200 may perform interleaving(or row permutation) processes in super frame units. In this case, thesuper_frame_size field indicates the number of RS frames configuring thesuper frame. Furthermore, the super_frame_size field corresponds to oneof the transmission parameters being transmitted along with the mobileservice data, when the corresponding mobile service data are transmittedto the receiving system from the transmitter 200. Herein, 2 reservedbits may be allocated after the super_frame_size field.

The burst_size field is a 6-bit field, which indicates the size of aburst. More specifically, when the transmitter 200 transmits the mobileservice data in burst units, the burst_size field indicates the numberof data groups configuring a burst section. The burst_size field alsocorresponds to one of the transmission parameters being transmittedalong with the mobile service data, when the corresponding mobileservice data are transmitted to the receiving system from thetransmitter 200. Herein, 1 reserved bit may be allocated after theburst_size field.

The turbo_code_mode field is a 3-bit field, which indicates the turbocode mode applied to each region within the data group. For example, thetransmitter 200 may group a plurality of mobile service data packets soas to configure a data group, and the data group may then be dividedinto a plurality of hierarchical regions. Also, a plurality of datagroups may be grouped to form a burst. At this point, a data group isdivided into a plurality of regions (e.g., regions A, B, and C), asshown in FIG. 11A and FIG. 11B. The method of dividing the regionswithin the data group and each of the regions will be described indetail with reference to FIG. 11A and FIG. 11B along with the detaileddescription of the transmitter 200. FIG. 6 illustrates a table showingan example of a turbo code mode being applied to regions A/B and toregion C within a data group. For example, when the value of theturbo_code_mode field is equal to ‘001’, the transmitter 200 encodes themobile service data that are to be allocated to regions A/B at a codingrate of ½ and encodes the mobile service data that are to be allocatedto region C at a coding rate of ¼.

The RS_code_mode field is a 4-bit field, which indicates the RS codemode applied to each region within the data group. For example, when adata group is divided into regions A, B, and C, as shown in FIG. 11A andFIG. 11B, FIG. 7A illustrates an example of a RS code mode being appliedto regions A/B. And, FIG. 7B illustrates an example of a RS code modebeing applied to region C. For example, when the value of theRS_code_mode field is equal to ‘1110’, the transmitter 200 performs(235,187)-RS encoding on a RS frame that is to be allocated to regionsA/B, thereby generating 48 parity bytes. The transmitter 200 thenperforms (223,187)-RS encoding on a RS frame that is to be allocated toregion C, thereby generating 36 parity bytes.

The order, position, and definition of the fields allocated to theSI_packet( ) field described in FIG. 4A are merely examples presented tofacilitate and simplify the understanding of the present invention. Inother words, the order, position, and definition of the fields allocatedto the SI_packet( ) field may be easily altered or modified by thesystem designer. Therefore, the present invention will not be limited tothe examples given in the above-described embodiment of the presentinvention.

FIG. 4B illustrates an example of a SI packet structure corresponding tomultiple mobile services. Herein, the SI packet may also be inserted inan OM_payload field within the OM packet of FIG. 3. At this point, theOM packet having the SI packet inserted therein may either be generatedfrom the SI packet generator 130, or be generated from the mobileservice multiplexer 150. Furthermore, the mobile service data packet andthe OM packet are multiplexed by the mobile service multiplexer 150 andthen outputted.

The SI_packet( ) field of FIG. 4B may include a number_of_services fieldand a transmission parameter field that is repeated in accordance withthe number_of_services field value.

More specifically, the number_of_services field is also assigned with 8bits. Herein, the number_of_services field indicates the type of mobileservice being multiplexed by the mobile service multiplexer 150. Forexample, when 4 different types of mobile service data are beinginputted, the value of the number_of_services field is equal to‘4(−00000100)’. The transmission parameter field may include aservice_id field, a program_number field, a burst_period field, asuper_frame_size field, a burst_size field, a turbo_code_mode field, anda RS_code_mode field. Herein, since the definition for each field withinthe transmission parameter field is identical to those shown in FIG. 4A,a detailed description of the same will be omitted for simplicity.

Meanwhile, in some occasion, based upon the number of mobile servicesand the transmission parameters included in each mobile service, all ofthe desired (or wanted) transmission parameters may not be transmittedto a single OM packet. In this case, one or more OM packets may be usedto transmit all transmission parameters. At this point, the OM packethaving the SI packet inserted therein may be inserted based upon aconstant cycle period.

FIG. 5 illustrates the syntax structure for transmitting transmissionparameters corresponding to all mobile service types to a single OMpacket, when a SI packet corresponding to a single mobile service typeis generated, as shown in FIG. 4A. More specifically, FIG. 5 illustratesan exemplary syntax structure of an OM packet corresponding to multiplemobile services. Herein, the 184 bytes excluding a 4-byte packet headermay include an OM_type field, a packet_number field, anumber_of_services field, and a SI_packet( ) field, which is repeated asmany times as the number_of_services field value. If the size of thefield including the OM_type field, the packet_number field, thenumber_of_services field, and the SI_packet( ) field, which is repeatedas many times as the number_of_services field value, is smaller than 183bytes, the remaining bytes may be filled with stuffing bytes by thestuffing_byte field following the following the corresponding field.Herein, the stuffing_byte field is repeated as many times as the lackingnumber of bytes, thereby maintaining the size of the OM_payload field ofthe corresponding OM packet to 183 bytes. For example, the stuffing_bytefield is an 8-bit field, which indicates data bytes used for filling theempty spaces within the corresponding field.

The OM_type field is an 8-bit field, which can indicate identificationinformation that can recognize the insertion of a SI packet within thecorresponding OM packet. The packet_number field is a 16-bit field,which identifies a count value of the corresponding packet among thetotal count value of 60 fields. The packet_number field may be used foridentifying the beginning (or starting) point of a burst period. Forexample, the packet_number field may recognize the beginning point of a60-field burst period. The number_of_services field is also assignedwith 8 bits. Herein, the number_of_services field indicates the type ofmobile service being multiplexed by the mobile service multiplexer 150.For example, when 4 different types of mobile service data are beinginputted, the value of the number_of_services field is equal to‘4(=00000100)’.

The SI_packet( ) field is repeated as many times as thenumber_of_services field value, thereby transmitting the transmissionparameters corresponding to each mobile service. Herein, the same fieldsincluded in the SI_packet( ) field shown in FIG. 4A may also be includedin the SI_Packet( ) of FIG. 5. For example, the SI_packet( ) field mayinclude a service_id field, a program_number field, a burst_periodfield, a super_frame_size field, a burst_size field, a turbo_code_modefield, and a RS_code_mode field. The order, position, and definition ofthe fields allocated to the payload field of the OM packet shown in FIG.5 are merely examples presented to facilitate and simplify theunderstanding of the present invention. In other words, the order,position, and definition of the fields allocated to the payload field ofthe OM packet may be easily altered or modified by the system designer.Therefore, the present invention will not be limited to the examplesgiven in the above-described embodiment of the present invention.

Meanwhile, the mobile services may each be identified by allocatingdifferent PIDs, none of which being used by any of the main services.More specifically, each mobile service is allocated with a unique PID.At this point, the transmitter 200 can refer to the PSI/PSIP table inorder to recognize a program map corresponding to the mobile service.And, in some occasion, when the SI packet generator 130 generates SIpackets (or OM packets) so that each SI packet can be multiplexed with amobile service data packet on a one-to-one (1:1) basis, the final datarate of the mobile service multiplexer 150 may not be equal to K Mbps.In this case, the null packet generator 140 generates null data packetsand outputs the generated null data packet to the mobile servicemultiplexer 150, thereby matching (or fixing) the final data rate of themobile service multiplexer to K Mbps.

Thereafter, the null data packet is transmitted to the transmitter 200and then deleted (or discarded). In other words, the null data packet isnot transmitted to the receiving system. For this, an identificationinformation for identifying the null data packet is required. Similarly,the identification information for identifying the null data packet mayuse a value that is pre-decided based upon an agreement between thetransmitting system and the receiving system. Alternatively, theidentification information for identifying the null data packet may beconfigured of a separate set of data. Furthermore, the identificationinformation for identifying the null data packet may also modify thevalue of a predetermined position within the null data packet and usethe modified value. For example, the null packet generator 140 maymodify the value of the synchronization byte within the header of thenull data packet and then use the modified value as the identificationinformation. Alternatively, the null packet generator 140 may set thetransport error_indicator flag field to ‘1’ and use this value as theidentification information.

In the embodiment of the present invention, thetransport_error_indicator flag field of the header within the null datapacket is used as the identification information for identifying thenull data packet. In this case, the transport_error_indicator flag fieldis set to ‘1’, and the transport_error_indicator flag fields included inall of the other data packets, apart from the null data packet, arereset to ‘0’, thereby identifying the null data packet. Any field valuethat can identify the null data packet may be used as the identificationinformation. Therefore, the present invention is not limited only to theexamples given in the description of the present invention.

PSI/PSIP for Mobile Service

Meanwhile, the PSI/PSIP tables generated from both the PSI/PSIPgenerator 110 for main service and PSI/PSIP generator 120 for mobileservice of the service multiplexer 100 correspond to system informationrequired by the receiving system for receiving and recoding the mainservice data and mobile service data. In some occasions, such systeminformation may also be referred to as service information. Morespecifically, the system information not only includes the informationon the system itself but may also include other types of information,such as channel information, program information, event information, andso on.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number. The STTtransmits information on the current data and timing information. TheRRT transmits information on region and consultation organs for programratings. The ETT transmits additional description of a specific channeland broadcast program. The EIT transmits information on virtual channelevents (e.g., program title, program start time, etc.). The DCCT/DCCSCTtransmits information associated with automatic (or direct) channelchange. And, the MGT transmits the versions and PID information of theabove-mentioned tables included in the PSIP.

At this point, the PAT for main service and the PAT for mobile servicemay each be generated independently (or separately). Alternatively, thePAT for main service and the PAT for mobile service may be combined and,then, generated as a single PAT. In order to do so, the PSI/PSIPgenerator 110 for main service and the PSI/PSIP generator 120 for mobileservice may be integrated. Also, even though the PAT for main serviceand the PAT for mobile service are combined so as to be generated as asingle PAT, the PMT for main service and the PMT for mobile service mayeach be generated independently (or separately).

For example, a PMT for main service and a PMT for mobile service may beequally allocated and, then, inputted to the transport multiplexer 160.In this case, the transport multiplexer 160 may change one PID among thetwo PMTs and may also correct (or modify) the PMT information includedin the PAT. Also, when a plurality of mobile service types exists, aplurality of PMTs may be generated. At this point, each PMT is given aunique PID. Furthermore, when identifying the main service data packetand the mobile service data packet by using the synchronization byte,the syntax, PID, and table ID of the PSI/PSIP table for mobile servicemay be used identically as those of the PSI/PSIP table for main service.

FIG. 8A illustrates PID and table ID of the PSI/PSIP tables used in themain service. Referring to FIG. 8A, the tables each having a fixed PIDvalue includes the PAT (e.g., 0x0000), the CAT (e.g., 0x0001), the MGT(e.g., 0x1FFB), the VCT (e.g., 0x1FFB), and the RRT (e.g., 0x1FFB).Also, in case of the tables each having variable PID values, the PIDvalues for the PMT and NIT are decided by the PAT, and the PID valuesfor the EIT, ETT, and RRT are decided by the MGT. Meanwhile, whenidentifying the main service data packet and the mobile service datapacket by using the PID, it is preferable to distinguish the PID for thePSI/PSIP tables for mobile service from the PID for the PSI/PSIP tablesfor main service.

FIG. 8B illustrates PID and table ID of the PSI/PSIP tables used in themobile service. The PIDs of PAT-E, CAT-E, MGT-E, VCT-E, and RRT-Edefined in FIG. 8B are different from the IDs of the correspondingtables shown in FIG. 8A. More specifically, referring to FIG. 8B, thetables each having a fixed PID value includes the PAT-e (e.g., 0x1FF7),the CAT-E (e.g., 0x1FF9), the MGT-E (e.g., 0x1FF8), the VCT-E (e.g.,0x1FF8), and the RRT-E (e.g., 0x1FF8). Also, in case of the tables eachhaving variable PID values, the PID values for the PMT-E and NIT-E aredecided by the PAT-E, and the PID values for the EIT-E, ETT-E, and RRT-Eare decided by the MGT-E. The PIDs shown in FIG. 8B are merelyexemplary, and other PID values that can be differentiated from thePSI/PSIP tables for the main service may be allocated as used. Referringto FIG. 8B, the syntax and table ID of each table may be usedidentically as those of the PSI/PSIP tables for main service.Furthermore, each of the PSI/PSIP tables for mobile service is requiredto be periodically multiplexed, so that the related information can beprovided to the transmitter 200 and the receiving system. And, themaximum multiplexing cycle for each table (i.e., maximum_cycle_time) maybe variably set based upon the characteristics of each table and thedata rates of the mobile service data.

FIG. 9 illustrates a block diagram showing an example of the transmitter200 according to an embodiment of the present invention. Herein, thetransmitter 200 includes a demultiplexer 211, an OM packet decoder 212,an input buffer 213 for main service, an input buffer 214 for mobileservice, a pre-processor 215, a packet multiplexer 216, a post-processor220, a synchronization (sync) multiplexer 230, and a transmission unit240. Herein, a data packet transmitted from the service multiplexer 100is inputted to the demultiplexer 211 of the transmitter 200. Then, thedemultiplexer 211 determines whether or not the data packet correspondsto a main service data packet or a mobile service data packet. The mainservice data packet identified by the demultiplexer 211 is provided tothe input buffer 213 for main service, and the mobile service datapacket identified by the demultiplexer 211 is provided to the inputbuffer 214 for mobile service. At this point, the demultiplexer 211 mayuse a plurality of methods for identifying (or determining) whether ornot the corresponding data packet is a main service data packet or amobile service data packet.

According to an embodiment of the present invention, the correspondingdata packet may be identified as either the main service data packet orthe mobile service data packet, based upon a PID value of the datapacket that is being inputted. More specifically, the demultiplexer 211provides data packets having PIDs allocated to main service data packetsto the input buffer 213 for main service. Similarly, the demultiplexer211 provides data packets having PIDs allocated to mobile service datapackets to the input buffer 214 for mobile service. The PID informationmay be extracted through a PSI/PSIP table transmitted from the servicemultiplexer 100.

According to another embodiment of the present invention, thedemultiplexer 211 may identify (or determine) the inputted data packetas one of the mobile service data packet and the main service datapacket, based upon the synchronization byte within the inputted datapacket. Additionally, the demultiplexer 211 also determines whether theinputted data corresponds to a null data packet or an OM packet havingan SI packet inserted therein. For example, the null data packet may beidentified by referring to a value of a transport_error_indicator flagfield of the inputted data packet. The null data packet identified bythe demultiplexer 211 is not processed. However, the identified datapacket is not provided to other blocks or to the receiving systemeither.

On the other hand, the OM packet may be identified by referring to thePID of the inputted data packet. For example, when the PID of theinputted data packet is equal to ‘0xFFA’, the demultiplexer 211determines the inputted data packet as an OM packet, thereby providingthe corresponding data packet to the OM packet decoder 212. The OMpacket decoder 212 parses the value of the OM_type field within the OMpacket, so as to verify whether or not a SI packet has been inserted inthe corresponding OM packet. IF the OM_type field value indicates thatthe SI packet has been inserted, the OM packet decoder 212 decodes thesubsequent OM_payload field, thereby extracting the transmissionparameters. The extracted transmission parameters are then provided toeach block (e.g., the pre-processor 215, the packet multiplexer 216,etc.) requiring specific transmission parameters. Thus, eachcorresponding block may adequately utilize each transmission parameter.

Herein, for example, the transmission parameters may include a mobileservice identification information, a super frame information, a burstsize information, a burst period information, a turbo code information,a RS code information, and so on (shown in FIG. 4A). The informationincluded in the transmission parameter is merely exemplary to facilitatethe understanding of the present invention. And, the adding and deletingof the information included in the transmission parameter may be easilymodified and changed by anyone skilled in the art. Therefore, thepresent invention is not limited to the examples proposed in thedescription set forth herein.

Meanwhile, the PSI/PSIP table for main service and the PSI/PSIP tablefor mobile service both transmitted from the service multiplexer 100 maybe directly transmitted to the receiving system without anymodification, or may be reconfigured an then transmitted to thereceiving system. For example, it is assumed that the PAT for mainservice and the PAT for mobile service are integrated a single PAT andthen transmitted. In this case, the input buffer 213 for main servicemay receive only the PAT having the information for mobile servicedeleted from the integrated PAT. Similarly, the input buffer 214 formobile service may receive only the PAT having the information for mainservice deleted from the integrated PAT.

The input buffer 213 for main service receives and temporarily storesthe main service data packet and the PSI/PSIP table for main service.Thus, the input buffer 213 for main service may perform packet jittermitigation, null packet insertion, and PCR adjustment. The input buffer214 for mobile service is provided as much as the number of mobileservices. Each input buffer 214 for mobile service receives andtemporarily stores the mobile service data packet and the PSI/PSIP tablefor mobile service. Accordingly, each input buffer 214 for mobileservice may perform null packet insertion and PCR adjustment. The outputof the input buffer 213 for main service is sent to the packetmultiplexer 216, and the output of the input buffer 214 for mobileservice passes through the pre-processor 215 and is then sent to thepacket multiplexer 216. The pre-processor 215 additional encoding on themobile service data packet, thereby enabling the mobile service data torespond more effectively to noise and channel environment that undergoesfrequent changes. The additionally encoded mobile service data are thenoutputted to the packet multiplexer 216.

FIG. 10 illustrates a block diagram of the pre-processor 215 accordingto an embodiment of the present invention. Herein, the pre-processor 215includes a data randomizer 401, a RS frame encoder 402, a blockprocessor 403, a group formatter 404, a data deinterleaver 405, and apacket formatter 406. The pre-processor 215 according to the embodimentof the present invention refers to the transmission parameter providedby the OM packet decoder 212, thereby performing additional encoding onthe inputted mobile service data. More specifically, the data randomizer401 receives mobile service data and randomizes the received mobileservice data, thereby outputting the processed data to the RS frameencoder 402. At this point, by having the data randomizer 401 randomizethe mobile service data, a later randomizing process on the mobileservice data performed by the data randomizer 221 of the post-processor220 may be omitted.

The RS frame encoder 402 groups a plurality of the received mobileservice data packets that have been randomized. Then, the RS frameencoder 402 performs at least one of an error correction encodingprocess and an error detection encoding process on the receivedrandomized mobile service data. Furthermore, the RS frame encoder 402may also group a plurality of RS frames so as to configure a superframe, thereby performing interleaving (or permutation) processes insuper frame units. Thus, by providing robustness on the mobile servicedata, the corresponding data may be able to respond to the severelyvulnerable and frequently changing frequency environment.

More specifically, when the RS frame encoder 402 performs rowpermutation based upon a predetermined rule for permuting each row ofthe super frame, the row positions within the super frame after the rowpermutation process may differ from the row positions within the superframe prior to the row permutation (or interleaving) process. Herein, byperforming the row permutation (or interleaving) process in super frameunits, even though the section having a plurality of errors occurringtherein becomes very long, and even though the number of errors includedin the RS frame that is to be decoded exceeds the extent of being ableto be corrected, the errors become dispersed within the entire superframe. Thus, the decoding ability is even more enhanced as compared to asingle RS frame.

In the RS frame encoder 402 according to the embodiment of the presentinvention, RS encoding is applied as the error correction encodingprocess, and cyclic redundancy check (CRC) encoding is applied as theerror detection encoding process. When performing RS encoding, paritydata that are to be used for error correction are generated. And, whenperforming CRC encoding, CRC data that are to be used for errordetection are generated. Also, in the present invention, the RS encodingcorresponds to the forward error correction (FEC) method. The FECcorresponds to a technique for compensating errors that occur during thetransmission process. The CRC data generated by CRC encoding may be usedfor indicating whether or not the mobile service data have been damagedby the errors while being transmitted through the channel. In thepresent invention, a variety of error detection coding methods otherthan the CRC encoding method may be used, or the error correction codingmethod may be used to enhance the overall error correction ability (orperformance) of the receiving system.

Herein, the RS frame encoder 402 refers to the pre-set transmissionparameter and/or refers to the transmission parameter provided from theOM packet decoder 212, thereby being able to perform processes includingRS frame configuration, RS encoding, CRC encoding, super frameconfiguration, and row permutation (or interleaving) in super frameunits. For example, when the transmission parameter within the RS codemode (shown in FIG. 7A and FIG. 7B) is equal to ‘1110’, the RS frameencoder 402 performs (235,187)-RS encoding on the RS frame that is to beallocated to regions A/B, thereby generating 48 parity data bytes.Alternatively, the RS frame encoder 402 performs (223,187)-RS encodingon the RS frame that is to be allocated to region C, thereby generating36 parity data bytes.

As described above, the mobile service data encoded by the RS frameencoder 402 are inputted to the block processor 403. The block processor403 then encodes the inputted mobile service data at a coding rate ofG/H (wherein, G is smaller than H (i.e., G<H)) and then outputted to thegroup formatter 404. More specifically, the block processor 403 dividesthe mobile service data being inputted in byte units into bit units.Then, the G number of bits is encoded to H number of bits. Thereafter,the encoded bits are converted back to byte units and then outputted.For example, if 1 bit of the input data is coded to 2 bits andoutputted, then G is equal to 1 and H is equal to 2 (i.e., G=1 and H=2).Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).Hereinafter, the former coding rate will be referred to as a coding rateof ½ (½-rate coding), and the latter coding rate will be referred to asa coding rate of ¼ (¼-rate coding), for simplicity.

Herein, when using the ¼ coding rate, the coding efficiency is greaterthan when using the ½ coding rate, and may, therefore, provide greaterand enhanced error correction ability. For such reason, when it isassumed that the data encoded at a ¼ coding rate in the group formatter404, which is located near the end portion of the system, are allocatedto a region in which the receiving performance may be deteriorated, andthat the data encoded at a ½ coding rate are allocated to a regionhaving excellent receiving performance, the difference in performancemay be reduced.

At this point, the block processor 403 may also receive signalinginformation, such as the transmission parameters. Herein, the signalinginformation is also encoding at the coding rate of ½ or the coding rateof ¼, which is similarly performed in the step of processing the mobileservice data. Afterwards, the signaling information is considered andtreated identically as the mobile service data. Meanwhile, the groupformatter 404 inserts mobile service data that are outputted from theblock processor 403 in corresponding regions within a data group, whichis configured in accordance with a pre-defined rule. Also, with respectto the data deinterleaving process, each place holder or known data arealso inserted in corresponding regions within the data group. At thispoint, the data group may be divided into at least one hierarchicalregion. Herein, the type of mobile service data being inserted to eachregion may vary depending upon the characteristics of each hierarchicalregion. For example, each region may be divided based upon the receivingperformance within the data group.

In an example given in the present invention, a data group is dividedinto A, B, and C regions in a data configuration prior to datadeinterleaving. At this point, the group formatter 404 allocates themobile service data, which are inputted after being RS encoded and blockencoded, to each of the corresponding regions by referring to thetransmission parameter. FIG. 11A illustrates an alignment of data afterbeing data interleaved and identified, and FIG. 11B illustrates analignment of data before being data interleaved and identified. Morespecifically, a data structure identical to that shown in FIG. 11A istransmitted to a receiving system. Also, the data group configured tohave the same structure as the data structure shown in FIG. 11A isinputted to the data deinterleaver 405.

As described above, FIG. 11A illustrates a data structure prior to datadeinterleaving that is divided into 3 regions, such as region A, regionB, and region C. Also, in the present invention, each of the regions Ato C is further divided into a plurality of regions. Referring to FIG.11A, region A is divided into 5 regions (A1 to A5), region B is dividedinto 2 regions (B1 and B2), and region C is divided into 3 regions (C1to C3). Herein, regions A to C are identified as regions having similarreceiving performances within the data group. Herein, the type of mobileservice data, which are inputted, may also vary depending upon thecharacteristic of each region.

In the example of the present invention, the data structure is dividedinto regions A to C based upon the level of interference of the mainservice data. Herein, the data group is divided into a plurality ofregions to be used for different purposes. More specifically, a regionof the main service data having no interference or a very lowinterference level may be considered to have a more resistant (orrobust) receiving performance as compared to regions having higherinterference levels. Additionally, when using a system inserting andtransmitting known data in the data group, and when consecutively longknown data are to be periodically inserted in the mobile service data,the known data having a predetermined length may be periodicallyinserted in the region having no interference from the main service data(e.g., region A). However, due to interference from the main servicedata, it is difficult to periodically insert known data and also toinsert consecutively long known data to a region having interferencefrom the main service data (e.g., region B and region C).

Hereinafter, examples of allocating data to region A (A1 to A5), regionB (B1 and B2), and region C (C1 to C3) will now be described in detailwith reference to FIG. 11A. The data group size, the number ofhierarchically divided regions within the data group and the size ofeach region, and the number of mobile service data bytes that can beinserted in each hierarchically divided region of FIG. 11A are merelyexamples given to facilitate the understanding of the present invention.Herein, the group formatter 404 creates a data group including places inwhich field synchronization data bytes are to be inserted, so as tocreate the data group that will hereinafter be described in detail.

More specifically, region A is a region within the data group in which along known data sequence may be periodically inserted, and in whichincludes regions wherein the main service data are not mixed (e.g., A1to A5). Also, region A includes a region A1 located between a fieldsynchronization region and the region in which the first known datasequence is to be inserted. The field synchronization region has thelength of one segment (i.e., 832 symbols).

For example, referring to FIG. 11A, 2428 bytes of the mobile servicedata may be inserted in region A1, 2580 bytes may be inserted in regionA2, 2772 bytes may be inserted in region A3, 2472 bytes may be insertedin region A4, and 2772 bytes may be inserted in region A5. Herein,trellis initialization data or known data, MPEG header, and RS parityare not included in the mobile service data of region A. As describedabove, when region A includes a known data sequence at both ends, thereceiving system uses channel information that can obtain known data orfield synchronization data, so as to perform equalization, therebyproviding enforced equalization performance.

Also, region B includes region B1 located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region A1), and region B2 located within8 segments behind the very last known data sequence which is inserted inthe data group. For example, 930 bytes of the mobile service data may beinserted in the region B1, and 1350 bytes may be inserted in region B2.Similarly, trellis initialization data or known data, MPEG header, andRS parity are not included in the mobile service data of region B. Incase of region B, the receiving system may perform equalization by usingchannel information obtained from the field synchronization region.Alternatively, the receiving system may also perform equalization byusing channel information that may be obtained from the last known datasequence, thereby enabling the system to respond to the channel changes.

Region C includes region C1 located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region A), region C2 located within 12segments including and following the 9^(th) segment of the very lastknown data sequence within the data group (chronologically located afterregion A), and region C3 located in 32 segments after the region C2. Forexample, 1272 bytes of the mobile service data may be inserted in theregion C1, 1560 bytes may be inserted in region C2, and 1312 bytes maybe inserted in region C3. Similarly, trellis initialization data orknown data, MPEG header, and RS parity are not included in the mobileservice data. Herein, region C (e.g., region C1) is locatedchronologically earlier than (or before) region A.

Since region C1 is located further apart from the field synchronizationregion which corresponds to the closest known data region, the receivingsystem may use the channel information obtained from the fieldsynchronization data when performing channel equalization.Alternatively, the receiving system may also use the most recent channelinformation of a previous data group. Furthermore, in region C2 andregion C3 located before region A, the receiving system may use thechannel information obtained from the last known data sequence toperform equalization. However, when the channels are subject to fast andfrequent changes, the equalization may not be performed perfectly.Therefore, the equalization performance of region C may be deterioratedas compared to that of region B.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor403 may encode the mobile service data, which are to be inserted to eachregion based upon the turbo code mode within the transmission parameter,at a different coding rate. For example, when the turbo code mode isequal to ‘011’ (as shown in FIG. 6), the block processor 403 may encodethe mobile service data, which are to be inserted in regions A1 to A5 ofregion A, at a coding rate of ½. Then, the group formatter 404 mayinsert the ½-rate encoded mobile service data to regions A1 to A5.

The block processor 403 may encode the mobile service data, which are tobe inserted in regions B1 and B2 of region B, at a coding rate of ¼having higher error correction ability as compared to the ½-coding rate.Then, the group formatter 404 inserts the ¼-rate coded mobile servicedata in region B1 and region B2. Furthermore, the block processor 403may encode the mobile service data, which are to be inserted in regionsC1 to C3 of region C, at a coding rate of ¼ or a coding rate havinghigher error correction ability than the ¼-coding rate. Then, the groupformatter 404 may either insert the encoded mobile service data toregions C1 to C3, as described above, or leave the data in a reservedregion for future usage.

Also, apart from the mobile service data, the group formatter 404 alsoinserts signaling information including the transmission parameter. Thetransmitter 200 transmits transmission parameters to the receivingsystem. For example, the transmission parameters include data groupinformation, region information within a data group, the number of RSframes configuring a super frame (i.e., a super frame size (SFS)), thenumber of RS parity data bytes (P) for each column within the RS frame,whether or not a checksum, which is added to determine the presence ofan error in a row direction within the RS frame, has been used, the typeand size of the checksum if the checksum is used (presently, 2 bytes areadded to the CRC), the number of data groups configuring one RSframe—since the RS frame is transmitted to one burst section, the numberof data groups configuring the one RS frame is identical to the numberof data groups within one burst (i.e., burst size (BS)), a turbo codemode, and a RS code mode.

Also, the transmission parameter required for receiving a burst includesa burst period—herein, one burst period corresponds to a value obtainedby counting the number of fields starting from the beginning of acurrent burst until the beginning of a next burst, a positioning orderof the RS frames that are currently being transmitted within a superframe (i.e., a permuted frame index (PFI)) or a positioning order ofgroups that are currently being transmitted within a RS frame (burst)(i.e., a group index (GI)), and a burst size. Depending upon the methodof managing a burst, the transmission parameter also includes the numberof fields remaining until the beginning of the next burst (i.e., time tonext burst (TNB)). And, by transmitting such information as thetransmission parameter, each data group being transmitted to thereceiving system may indicate a relative distance (or number of fields)between a current position and the beginning of a next burst. Thediverse information included in the transmission parameter merelycorresponding to examples given to facilitate the understanding of thepresent invention. Therefore, the proposed examples do not limit thescope or spirit of the present invention and may be easily varied ormodified by anyone skilled in the art.

In addition, apart from the encoded mobile service data outputted fromthe block processor 403, as shown in FIG. 11A, the group formatter 404also inserts MPEG header place holders, non-systematic RS parity placeholders, main service data place holders, which are related to datadeinterleaving in a later process. Herein, the main service data placeholders are inserted because the mobile service data bytes and the mainservice data bytes are alternately mixed with one another in region Band region C, based upon the input of the data deinterleaver. Forexample, based upon the data outputted after the data-deinterleavingprocess, the place holder for the MPEG header may be allocated at thevery beginning of each packet.

Furthermore, the group formatter 404 either inserts known data generatedin accordance with a pre-determined method or inserts known data placeholders for inserting the known data in a later process. Additionally,place holders for initializing the trellis encoding module 226 are alsoinserted in the corresponding regions. For example, the initializationdata place holders may be inserted in the beginning of the known datasequence. Herein, the size of the mobile service data that can beinserted in a data group may vary in accordance with the sizes of thetrellis initialization data or known data (or known data place holders),MPEG header place holders, and RS parity place holders.

The data outputted from the group formatter 404 are inputted to the datadeinterleaver 405. And, the data deinterleaver 405 deinterleaves data byperforming an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 406. More specifically, when the data and data placeholders within the data group configured as shown in FIG. 11A aredeinterleaved by the data deinterleaver 405, the data group beingoutputted to the packet formatter 406 is configured as shown in FIG.11B. The packet formatter 406 removes the main service data placeholders and the RS parity place holders that were allocated for thedeinterleaving process from the deinterleaved data being inputted. Then,the packet formatter 406 groups the remaining portion and replaces the4-byte MPEG header place holder with an MPEG header having a null packetPID (or a PID that is not used in the main service data packet).

Also, when the group formatter 404 inserts known data place holders, thepacket formatter 406 may insert actual known data in the known dataplace holders, or may directly output the known data place holderswithout any modification in order to make replacement insertion in alater process. Thereafter, the packet formatter 406 identifies the datawithin the packet-formatted data group, as described above, as a188-byte unit mobile service data packet (i.e., MPEG TS packet), whichis then provided to the packet multiplexer 216.

The packet multiplexer 216 multiplexes the mobile service data packetoutputted from the pre-processor 215 and the main service data packetoutputted from the input buffer 213 in accordance with a pre-definedmultiplexing method. Then, the packet multiplexer 216 outputs themultiplexed data packets to the data randomizer 221 of thepost-processor 220. Herein, the multiplexing method may vary inaccordance with various variables of the system design. One of themultiplexing methods of the packet multiplexer 216 consists of providinga burst-on section and a burst-off section along a time axis and, then,transmitting a plurality of data groups during a burst-on section andtransmitting only the main service data during a burst-off section. Atthis point, main service data may also be transmitted in the burst-onsection. Furthermore, the packet multiplexer 216 can refer totransmission parameters (e.g., information such as burst size or burstperiod) so as to determine the number and cycle periods of data groupsincluded in a single burst.

In this case, mobile service data and main service data co-exist in aburst-on section, and only the main service data exist in the burst-offsection. Therefore, the main service data section transmitting the mainservice data exist in both the burst-on section and the burst-offsection. At this point, the number of main service data packets includedin the main service data section within the burst-on section and thenumber of main service data packets included in the main service datasection within the burst-off section may be equal to or different fromone another. When the mobile service data are transmitted in burstunits, as described above, a receiving system that only receives themobile service data may turn on the power only during the burst-onsection so as to receive the corresponding data. Also, in this case, thereceiving system may turn off the power during burst-off sections,thereby preventing the main service data from being received. Thus, thereceiving system is capable of reducing excessive power consumption.

However, since a data group including mobile service data in-between thedata bytes of the main service data during the packet multiplexingprocess, the shifting of the chronological position (or place) of themain service data packet becomes relative. Also, a system object decoder(i.e., MPEG decoder) for processing the main service data of thereceiving system, receives and decodes only the main service data andrecognizes the mobile service data packet as a null data packet.Therefore, when the system object decoder of the receiving systemreceives a data group including mobile service data and a main servicedata packet that is multiplexed with the data group, a packet jitteroccurs.

At this point, since a multiple-level buffer for the video data existsin the system object decoder and the size of the buffer is relativelylarge, the packet jitter generated from the packet multiplexer 216 doesnot cause any serious problem in case of the video data. However, sincethe size of the buffer for the audio data is relatively small, thepacket jitter may cause some problem. More specifically, due to thepacket jitter, an overflow or underflow may occur in the buffer for themain service data of the receiving system (e.g., the buffer for theaudio data). Therefore, the input buffer 213 for main service re-adjuststhe relative position of the main service data packet so that theoverflow or underflow does not occur in the system object decoderincluded in the receiving system.

In the present invention, examples of repositioning places for the audiodata packets within the main service data in order to minimize theinfluence on the operations of the audio buffer will be described indetail. The input buffer 213 for main service repositions audio packetsof the main service data section so that the audio data packets of themain service can be positioned as equally and uniformly as possible. Thestandard for repositioning the audio data packets in the main servicedata performed by the input buffer 213 for main service will now bedescribed Herein, it is assumed that the input buffer 213 for mainservice knows the same multiplexing information as that of the packetmultiplexer 216, which is placed further behind the input buffer 213 formain service.

Firstly, if one audio data packet exists in the main service datasection (e.g., the main service data section positioned between two datagroups) within the burst section, the audio data packet is positioned atthe very beginning of the main service data section. Alternatively, iftwo audio data packets exist in the corresponding data section, oneaudio data packet is positioned at the very beginning and the otheraudio data packet is positioned at the very end of the main service datasection. Further, if more than three audio data packets exist, one audiodata packet is positioned at the very beginning of the main service datasection, another is positioned at the very end of the main service datasection, and the remaining audio data packets are positioned between thefirst and last audio data packets at equal intervals.

Secondly, during the main service data section before the beginning of aburst section, the audio data packet is placed at the very end of themain service data section. Thirdly, during a main service data sectionafter the end of burst section, the audio data packet is positioned atthe very beginning of the main service data section. And, finally, thedata packets other than audio data packets are positioned to vacantspaces (i.e., spaces that are not designated for the audio data packets)in accordance with the inputted order. Meanwhile, when the positions ofthe main service data packets are relatively re-adjusted, associatedprogram clock reference (PCR) values may also be modified accordingly.The PCR value corresponds to a time reference value for synchronizingthe time of the MPEG decoder. Herein, the PCR value is inserted in aspecific region of a TS packet and then transmitted. In the embodimentof the present invention, the input buffer 213 for main service may alsoperform the function of correcting (or modifying) the PCR value.

The data outputted from the input buffer 213 for main service areinputted to the packet multiplexer 216. As described above, the packetmultiplexer 216 multiplexes the main service data packet outputted fromthe input buffer 213 for main service with the mobile service datapacket outputted from the pre-processor 215 into a burst structure inaccordance with a pre-determined multiplexing rule. Then, the packetmultiplexer 216 outputs the multiplexed data packets to the datarandomizer 221 of the post-processor 220.

If the inputted data correspond to the main service data packet, thedata randomizer 221 performs the same randomizing process as that of theconventional randomizer. More specifically, the synchronization bytewithin the main service data packet is deleted. Then, the remaining 187data bytes are randomized by using a pseudo random byte generated fromthe data randomizer 221. Thereafter, the randomized data are outputtedto the RS encoder/non-systematic RS encoder 222. On the other hand, ifthe inputted data correspond to the mobile service data packet, the datarandomizer 221 deletes the synchronization byte from the 4-byte MPEGheader included in the mobile service data packet and, then, performsthe randomizing process only on the remaining 3 data bytes of the MPEGheader. Thereafter, the randomized data bytes are outputted to the RSencoder/non-systematic RS encoder 222.

Additionally, the randomizing process is not performed on the remainingportion of the mobile service data excluding the MPEG header. In otherwords, the remaining portion of the mobile service data packet isdirectly outputted to the RS encoder/non-systematic RS encoder 222without being randomized. This is because a randomizing process hasalready been performed on the mobile service data in the data randomizer401. Also, the data randomizer 221 may or may not perform a randomizingprocess on the known data (or known data place holders) and theinitialization data place holders included in the mobile service datapacket.

The RS encoder/non-systematic RS encoder 222 performs an RS encodingprocess on the data being randomized by the data randomizer 221 or onthe data bypassing the data randomizer 221, so as to add 20 bytes of RSparity data. Thereafter, the processed data are outputted to the datainterleaver 223. Herein, if the inputted data correspond to the mainservice data packet, the RS encoder/non-systematic RS encoder 222performs the same systematic RS encoding process as that of theconventional VSB system, thereby adding the 20-byte RS parity data atthe end of the 187-byte data. Alternatively, if the inputted datacorrespond to the mobile service data packet, the RSencoder/non-systematic RS encoder 222 performs a non-systematic RSencoding process. At this point, the 20-byte RS parity data obtainedfrom the non-systematic RS encoding process are inserted in apre-decided parity byte place within the mobile service data packet.

The data interleaver 223 corresponds to a byte unit convolutionalinterleaver. The output of the data interleaver 223 is inputted to theparity replacer 224 and to the non-systematic RS encoder 225. Meanwhile,a process of initializing a memory within the trellis encoding module226 is primarily required in order to decide the output data of thetrellis encoding module 226, which is located after the parity replacer224, as the known data pre-defined according to an agreement between thereceiving system and the transmitting system. More specifically, thememory of the trellis encoding module 226 should first be initializedbefore the received known data sequence is trellis-encoded. At thispoint, the beginning portion of the known data sequence that is receivedcorresponds to the initialization data place holder and not to theactual known data. Herein, the initialization data place holder has beenincluded in the data by the group formatter 404 in an earlier process.Therefore, the process of generating initialization data and replacingthe initialization data place holder of the corresponding memory withthe generated initialization data are required to be performedimmediately before the inputted known data sequence is trellis-encoded.

Additionally, a value of the trellis memory initialization data isdecided and generated based upon a memory status of the trellis encodingmodule 226. Further, due to the newly replaced initialization data, aprocess of newly calculating the RS parity and replacing the RS parity,which is outputted from the data interleaver 223, with the newlycalculated RS parity is required. Therefore, the non-systematic RSencoder 225 receives the mobile service data packet including theinitialization data place holders, which are to be replaced with theactual initialization data, from the data interleaver 223 and alsoreceives the initialization data from the trellis encoding module 226.

Among the inputted mobile service data packet, the initialization dataplace holders are replaced with the initialization data, and the RSparity data that are added to the mobile service data packet.Thereafter, a new non-systematic RS parity is calculated and thenoutputted to the parity replacer 224. Accordingly, the parity replacer224 selects the output of the data interleaver 223 as the data withinthe mobile service data packet, and the parity replacer 224 selects theoutput of the non-systematic RS encoder 225 as the RS parity data. Then,the selected data are outputted to the trellis encoding module 226.

Meanwhile, if the main service data packet is inputted or if the mobileservice data packet, which does not include any initialization dataplace holders that are to be replaced, is inputted, the parity replacer224 selects the data and RS parity that are outputted from the datainterleaver 223. Then, the parity replacer 224 directly outputs theselected data to the trellis encoding module 226 without anymodification. The trellis encoding module 226 converts the byte-unitdata to symbol units and performs a 12-way interleaving process so as totrellis-encode the received data. Thereafter, the processed data areoutputted to the synchronization multiplexer 230. The synchronizationmultiplexer 230 inserts a field synchronization signal and a segmentsynchronization signal to the data outputted from the trellis encodingmodule 226 and, then, outputs the processed data to the pilot inserter241 of the transmission unit 240. Herein, the data having a pilotinserted by the pilot inserter 241 are modulated by the modulator 242 inaccordance with a pre-decided modulating method (e.g., VSB method).Thereafter, the modulated data are transmitted to each receiving systemthrough the radio frequency (RF) up-converter 243.

FIG. 12 illustrates a block diagram showing a structure of a receivingsystem according to the present invention. The receiving system of FIG.12 uses transmission parameters and known data information, which aretransmitted by the transmitting system, so as to perform carrierrecovery, timing recovery, frame synchronization recovery, and channelequalization, thereby enhancing the receiving performance.

Referring to FIG. 12, the receiving system includes a tuner 601, ademodulator 602, an equalizer 603, a known data detector (or knownsequence detector) 604, a block decoder 605, a data deformatter 606, aRS frame decoder 607, a derandomizer 608, a data deinterleaver 609, a RSdecoder 610, and a data derandomizer 611. Herein, for simplicity of thedescription of the present invention, the data deformatter 606, the RSframe decoder 607, and the derandomizer 608 will be collectivelyreferred to as a mobile service data processing unit. And, the datadeinterleaver 609, the RS decoder 610, and the data derandomizer 611will be collectively referred to as a main service data processing unit.

More specifically, the tuner 601 tunes a frequency of a particularchannel and down-converts the tuned frequency to an intermediatefrequency (IF) signal. Then, the tuner 601 outputs the down-converted IFsignal to the demodulator 602 and the known sequence detector 604. Thedemodulator 602 performs self gain control, carrier recovery, and timingrecovery processes on the inputted IF signal, thereby modifying the IFsignal to a baseband signal. The equalizer 603 compensates thedistortion of the channel included in the demodulated signal and thenoutputs the error-compensated signal to the block decoder 605.

At this point, the known sequence detector 604 detects the knownsequence place inserted by the transmitting end from the input/outputdata of the demodulator 602 (i.e., the data prior to the demodulationprocess or the data after the demodulation process). Thereafter, theplace information (or position indicator) along with the symbol sequenceof the known data, which are generated from the detected place, isoutputted to the demodulator 602 and the equalizer 603. Also, the knownsequence detector 604 outputs a set of information to the block decoder605. This set of information is used to allow the block decoder 605 ofthe receiving system to identify the mobile service data that areprocessed with additional encoding from the transmitting system and themain service data that are not processed with additional encoding.

In addition, although the connection status is not shown in FIG. 12, theinformation detected from the known sequence detector 604 may be usedthroughout the entire receiving system and may also be used in the datadeformatter 606 and the RS frame decoder 607. The demodulator 602 usesthe known data (or sequence) position indicator and the known datasymbol sequence during the timing and/or carrier recovery, therebyenhancing the demodulating performance. Similarly, the equalizer 603uses the known sequence position indicator and the known data symbolsequence so as to enhance the equalizing performance. Moreover, thedecoding result of the block decoder 605 may be fed-back to theequalizer 603, thereby enhancing the equalizing performance.

The equalizer 603 may perform channel equalization by using a pluralityof methods. An example of estimating a channel impulse response (CIR) inthe field synchronization section and the known data section, so as toperform channel equalization will be given in the description of thepresent invention. Most particularly, an example of estimating the CIRin accordance with each region within the data group, which ishierarchically divided and transmitted from the transmitting system, andapplying each CIR differently will also be described herein.Furthermore, by using the known data, the place and contents of which isknown in accordance with an agreement between the transmitting systemand the receiving system, and the field synchronization data, so as toestimate the CIR, the present invention may be able to perform channelequalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions A to C, as shown in FIG. 11A. More specifically, inthe example of the present invention, each region A, B, and C arefurther divided into regions A1 to A5, regions B1 and B2, and regions C1to C3, respectively. Referring to FIG. 11A, the CIR that is estimatedfrom the field synchronization data in the data structure is referred toas CIR_FS. Alternatively, the CIRs that are estimated from each of the 5known data sequences existing in region A are sequentially referred toas CIR_N0, CIR_N1, CIR_N2, CIR_N3, and CIR_N4.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known, extrapolation refers to estimating a function valueof a point outside of the section between points Q and S. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

More specifically, in case of region C1, any one of the CIR_N4 estimatedfrom a previous data group, the CIR_FS estimated from the current datagroup that is to be processed with channel equalization, and a new CIRgenerated by extrapolating the CIR_FS of the current data group and theCIR_N0 may be used to perform channel equalization. Alternatively, incase of region B1, a variety of methods may be applied as described inthe case for region C1. For example, a new CIR created by linearlyextrapolating the CIR_FS estimated from the current data group and theCIR_N0 may be used to perform channel equalization. Also, the CIR_FSestimated from the current data group may also be used to performchannel equalization. Finally, in case of region A1, a new CIR may becreated by interpolating the CIR_FS estimated from the current datagroup and CIR_N0, which is then used to perform channel equalization.Furthermore, any one of the CIR_FS estimated from the current data groupand CIR_N0 may be used to perform channel equalization.

In case of regions A2 to A5, CIR_N(i−1) estimated from the current datagroup and CIR_N(i) may be interpolated to create a new CIR and use thenewly created CIR to perform channel equalization. Also, any one of theCIR_N(i−1) estimated from the current data group and the CIR_N(i) may beused to perform channel equalization. Alternatively, in case of regionsB2, C2, and C3, CIR_N3 and CIR_N4 both estimated from the current datagroup may be extrapolated to create a new CIR, which is then used toperform the channel equalization process. Furthermore, the CIR_N4estimated from the current data group may be used to perform the channelequalization process. Accordingly, an optimum performance may beobtained when performing channel equalization on the data inserted inthe data group. The methods of obtaining the CIRs required forperforming the channel equalization process in each region within thedata group, as described above, are merely examples given to facilitatethe understanding of the present invention. A wider range of methods mayalso be used herein. And, therefore, the present invention will not onlybe limited to the examples given in the description set forth herein.

Meanwhile, if the data being inputted to the block decoder 605 afterbeing channel equalized from the equalizer 603 correspond to the mobileservice data having block encoding and trellis encoding performedthereon by the transmitting system (i.e., data within the RS frame, andsignaling information data), trellis decoding and block decodingprocesses are performed on the inputted data as inverse processes of thetransmitting system. Alternatively, if the data being inputted to theblock decoder 605 correspond to the main service data having onlytrellis encoding performed thereon, and not the block encoding (e.g.,main service data), only the trellis decoding process is performed onthe inputted data as the inverse process of the transmitting system.

The data trellis-decoded and block-decoded by the block decoder 605 areinputted to the data deformatter 606. The block decoder 605 removes theknown data, trellis initialization data, and MPEG header, which areinserted in the data group, and the RS parity, which is added by the RSencoder/non-systematic RS encoder or non-systematic RS encoder of thetransmitting system from the data included in the data group. Then, theprocessed data are outputted to the data deformatter 606. Herein, theremoval of the data may be performed before the block decoding process,or may be performed during or after the block decoding process. If thetransmitting system includes signaling information in the data groupupon transmission, the signaling information is outputted to the datadeformatter 606.

Meanwhile, the trellis-decoded data transmitted from the block decoder605 are outputted to the data deinterleaver 609. At this point, the datatrellis-decoded by the block decoder 605 and then outputted to the datadeinterleaver 609 may include the main service data as well as the datawithin the RS frame and signaling information data. RS parity data,which are added by the transmitting system after the pre-processor 215may also be included in the data being outputted to the datadeinterleaver 609. In this case, the trellis decoder should be providedbefore the data deinterleaver 609. If the inputted data correspond tothe trellis-encoded data that have not been block-encoded by thetransmitting system, the block decoder 605 performs Viterbi decoding onthe inputted data so as to output a hard decision value or to perform ahard-decision on a soft decision value, thereby outputting the result.On the other hand, if the inputted data correspond to the data bothtrellis-encoded and block-encoded by the transmitting system, the blockdecoder 605 outputs a soft decision value with respect to the inputteddata.

In other words, if the inputted data correspond to the datablock-encoded by the block processor 403 of the transmitting system andthe data trellis-encoded by the trellis encoding module 256 of thetransmitting system, the block decoder 605 performs trellis-decoding andblock-decoding processes on the input data as inverse processes of thetransmitting system. At this point, the RS frame encoder of thetransmitting system may be viewed as an external code. And, the trellisencoding module may be viewed as an internal code. In order to maximizethe performance of the external code when decoding such concatenatedcodes, the decoder of the internal code should output a soft decisionvalue.

Meanwhile, the data deinterleaver 609, the RS decoder 610, and the dataderandomizer 611 are blocks required for receiving the main servicedata. Therefore, the above-mentioned blocks may not be required in thestructure of a receiving system that only receives the mobile servicedata. The data deinterleaver 609 performs an inverse process of the datainterleaver included in the transmitting system. In other words, thedata deinterleaver 609 deinterleaves the main service data outputtedfrom the block decoder 605 and outputs the deinterleaved main servicedata to the RS decoder 610. The data being inputted to the datadeinterleaver 609 may include main service data, as well as mobileservice data, known data, RS parity data, and an MPEG header. At thispoint, among the inputted data, only the main service data and the RSparity data added to the main service data packet may be outputted tothe RS decoder 610. Also, all data outputted after the data derandomizer611 may all be removed with the exception for the main service data. Inthe embodiment of the present invention, only the main service data andthe RS parity data added to the main service data packet are inputted tothe RS decoder 610.

The RS decoder 610 performs a systematic RS decoding process on thedeinterleaved data and outputs the processed data to the dataderandomizer 611. The data derandomizer 611 receives the output of theRS decoder 610 and generates a pseudo random data byte identical to thatof the randomizer included in the transmitting system. Thereafter, thedata derandomizer 611 performs a bitwise exclusive OR (XOR) operation onthe generated pseudo random data byte, thereby inserting the MPEGsynchronization bytes to the beginning of each packet so as to outputthe data in 188-byte main service data packet units.

Meanwhile, the data being outputted from the block decoder 605 to thedata deformatter 606 are inputted in the form of a data group. At thispoint, the data deformatter 606 already knows the structure of the datathat are to be inputted and is, therefore, capable of identifying thesignaling information, which includes the transmission parameters, andthe mobile service data from the data group. Thereafter, the datadeformatter 606 outputs the identified signaling information to a block(not shown) for processing the signaling information and outputs theidentified mobile service data to the RS frame decoder 607. Morespecifically, the RS frame decoder 607 receives only the RS-encoded andCRC-encoded mobile service data that are transmitted from the datadeformatter 606.

The RS frame encoder 607 performs an inverse process of the RS frameencoder included in the transmitting system so as to correct the errorwithin the RS frame. Then, the RS frame decoder 607 adds the 1-byte MPEGsynchronization service data packet, which had been removed during theRS frame encoding process, to the error-corrected mobile service datapacket. Thereafter, the processed data packet is outputted to thederandomizer 608. The derandomizer 608 performs a derandomizing process,which corresponds to the inverse process of the randomizer included inthe transmitting system, on the received mobile service data.Thereafter, the derandomized data are outputted, thereby obtaining themobile service data transmitted from the transmitting system.

As described above, the digital broadcasting system and method ofprocessing data according to the present invention have the followingadvantages. More specifically, the present invention is robust against(or resistant to) any error that may occur when transmitting mobileservice data through a channel. And, the present invention is alsohighly compatible to the conventional system. Moreover, the presentinvention may also receive the mobile service data without any erroreven in channels having severe ghost effect and noise.

Additionally, by performing error correction encoding and errordetection encoding processes on the mobile service data and transmittingthe processed data, the present invention may provide robustness to themobile service data, thereby enabling the data to effectively respond tothe frequent change in channels. Also, when the present inventionmultiplexes the main service data and the mobile service data in a burststructure, a relative position of a main service data packet isre-adjusted and then multiplexed, thereby mitigating packet jitter,which may occur when the receiving system receives the multiplexed mainservice data packet.

Moreover, when the main service data and the mobile service data aremultiplexed by the service multiplexer within the transmitting system,and when the multiplexed data are transmitted to the transmitter, thepresent invention transmits the mobile service-related informationthrough the OM packet. Thus, the present invention may match (or fix)the data rate of the final output data of the service multiplexer to aconstant data rate. The present invention may also enable thetransmitter to process the mobile service data more easily. Furthermore,the present invention is even more effective when applied to mobile andportable receivers, which are also liable to a frequent change inchannel and which require protection (or resistance) against intensenoise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A digital broadcast receiver, comprising: a tunerconfigured to receive a broadcast signal comprising mobile service data,wherein the broadcast signal is transmitted from a broadcast transmitterby: generating a Reed-Solomon (RS) frame by RS-encoding an RS framepayload with an RS code of (187+P, 187) and Cyclic Redundancy Check(CRC)-encoding the RS-encoded RS frame payload, thereby adding P bytesof first parity data at bottom ends of columns of the RS frame payloadand adding 2 bytes of CRC data at right ends of rows of the RS framepayload including the first parity data, wherein the RS frame payloadincludes mobile service data, and wherein P is one of 24, 36, and 48,mapping, by a group formatter, a portion of the RS frame into at leastone region of a first data group that has a plurality of regions, thefirst data group including a plurality of segments, wherein a number ofmobile service data in an Nth segment of the first data group is lessthan a number of mobile service data in an (N+1)th segment of the firstdata group, wherein the number of mobile service data in the (N+1)thsegment of the first data group is less than a number of mobile servicedata in an (N+2)th segment of the first data group, wherein the firstdata group further includes signaling information on a transmissionparameter, and wherein the signaling information includes an RS codemode field indicating the RS code for the RS frame, trellis-encoding, bya trellis encoder, data being outputted from the group formatter, thetrellis encoder having at least one memory that is initialized at eachstart of known data sequences, and multiplexing the trellis-encoded datawith field synchronization data and segment synchronization data; ademodulator configured to perform demodulating on the broadcast signal;and a decoder configured to perform decoding on the demodulatedbroadcast signal.
 2. The digital broadcast receiver of claim 1, whereinthe group formatter adds the known data sequences to the first datagroup.
 3. The digital broadcast receiver of claim 2, wherein the groupformatter inserts place holders for second parity data and MPEG headerdata to the first data group.
 4. The digital broadcast receiver of claim3, further comprising: a packet formatter configured to remove the placeholders for the second parity data from a second data group generated byde-interleaving the first data group and replace the place holders forthe MPEG header data with the MPEG header data in the second data group;and an RS encoder configured to RS-encode the second data group thatincludes the MPEG header data so as to add the second parity data to thesecond data group.
 5. The digital broadcast receiver of claim 4, furthercomprising an interleaver configured to interleave the second datagroup.
 6. The digital broadcast receiver of claim 1, wherein thesignaling information further includes a turbo code mode fieldindicating an outer code mode for each region of the first data group.7. A method of processing broadcast data in a digital broadcastreceiver, the method comprising: receiving, by a tuner, a broadcastsignal comprising mobile service data, wherein the broadcast signal istransmitted from a broadcast transmitter by: generating a Reed-Solomon(RS) frame by RS-encoding an RS frame payload with an RS code of (187+P,187) and Cyclic Redundancy Check (CRC)-encoding the RS-encoded RS framepayload, thereby adding P bytes of first parity data at bottom ends ofcolumns of the RS frame payload and adding 2 bytes of CRC data at rightends of rows of the RS frame payload including the first parity data,wherein the RS frame payload includes mobile service data, and wherein Pis one of 24, 36, and 48, mapping, by a group formatter, a portion ofthe RS frame into at least one region of a first data group that has aplurality of regions, the first data group including a plurality ofsegments, wherein a number of mobile service data in an Nth segment ofthe first data group is less than a number of mobile service data in an(N+1)th segment of the first data group, wherein the number of mobileservice data in the (N+1)th segment of the first data group is less thana number of mobile service data in an (N+2)th segment of the first datagroup, wherein the first data group further includes signalinginformation on a transmission parameter, and wherein the signalinginformation includes an RS code mode field indicating the RS code forthe RS frame, trellis-encoding, by a trellis encoder, data beingoutputted from the group formatter, the trellis encoder having at leastone memory that is initialized at each start of known data sequences,and multiplexing the trellis-encoded data with field synchronizationdata and segment synchronization data; demodulating the broadcastsignal; and decoding the demodulated broadcast signal.
 8. The method ofclaim 7, wherein the group formatter adds the known data sequences tothe first data group.
 9. The method of claim 8, wherein the groupformatter inserts place holders for second parity data and MPEG headerdata to the first data group.
 10. The method of claim 9, furthercomprising: removing the place holders for the second parity data from asecond data group generated by de-interleaving the first data group;replacing the place holders for the MPEG header data with the MPEGheader data in the second data group; and RS-encoding the second datagroup that includes the MPEG header data so as to add the second paritydata to the second data group.
 11. The method of claim 10, furthercomprising interleaving the second data group.
 12. The method of claim7, wherein the signaling information further includes a turbo code modefield indicating an outer code mode for each region of the first datagroup.
 13. A method of processing data in a broadcast transmitter, themethod comprising: randomizing broadcast service data for a service;performing permutation on the randomized broadcast service data;encoding signaling information; modulating data of a frame including thepermuted broadcast service data and the encoded signaling information;and transmitting a broadcast signal including the modulated data,wherein error detection encoding is performed selectively on therandomized broadcast service data, wherein, when CRC encoding as theerror detection encoding is performed, CRC data are added to therandomized broadcast service data, wherein the signaling informationincludes information for identifying whether or not the CRC encoding isperformed, wherein the frame further includes known data, wherein theknown data are categorized into a first pattern of known data and asecond pattern of known data other than the first pattern of known data,and wherein at least one of the first pattern of known data and thesecond pattern of known data are used for channel estimation in abroadcast receiver.
 14. The method of claim 13, further comprising:performing error correction encoding on the broadcast service data toadd a number of parity data, wherein the signaling information furtherincludes information of the number of parity data.
 15. The method ofclaim 13, wherein the signaling information further includesidentification information to identify the service.
 16. The method ofclaim 13, further comprising: interleaving the broadcast service data.17. The method of claim 13, further comprising: identifying a null datapacket included in an input stream that includes the null data packetand a broadcast service data packet, the broadcast service data packetincluding the broadcast service data; and deleting the identified nulldata packet in the input stream.
 18. A broadcast transmitter forprocessing data, the broadcast transmitter comprising: a randomizer forrandomizing broadcast service data for a service; a first encoder forperforming permutation on the randomized broadcast service data; asecond encoder for encoding signaling information; a modulator formodulating data of a frame the permuted broadcast service data and theencoded signaling information; and a transmitting unit for transmittinga broadcast signal including the modulated data, wherein error detectionencoding is performed selectively on the randomized broadcast servicedata, wherein, when CRC encoding as the error detection encoding isperformed, CRC data are added to the randomized broadcast service data,wherein the signaling information includes information for identifyingwhether or not the CRC encoding is performed, wherein the frame furtherincludes known data, wherein the known data are categorized into a firstpattern of known data and a second pattern of known data other than thefirst pattern of known data, and wherein at least one of the firstpattern of known data and the second pattern of known data are used forchannel estimation in a broadcast receiver.
 19. The broadcasttransmitter of claim 18, wherein the first encoder further performserror correction encoding on the broadcast service data to add a numberof parity data, and wherein the signaling information further includesinformation of the number of parity data.
 20. The broadcast transmitterof claim 18, wherein the signaling information further includesidentification information to identify the service.
 21. The broadcasttransmitter of claim 18, further comprising: an interleaver forinterleaving the broadcast service data.
 22. The broadcast transmitterof claim 18, further comprising: a demultiplexer for identifying a nulldata packet included in an input stream that includes the null datapacket and a broadcast service data packet, the broadcast service datapacket including the broadcast service data, and deleting the identifiednull data packet in the input stream.